320 Mr. A. Tulk ow the Anatomy of Phalangium Opilio. 



annuli are paler in colour than the rest, and nearly obsolete. 

 Anteriorly the ovipositor terminates by two organs of peculiar 

 construction. These consist of a pair of short, obtuse and some- 

 what conical appendages, freely articulated to the last ring, and 

 opposed to each other so as to constitute a kind of forceps, which 

 must serve admirably for laying hold of the eggs as they issue 

 from the ovipositor, and depositing them in their appropriate nidus. 

 They are composed each of two joints : the basal (PI. V. fig. 29. b), 

 somewhat quadrate in form, has its outer border elliptical and 

 provided with two or three bristles, equalling it in width and 

 standing out at right angles from the side of the joint. Its outer 

 side is dark, and of a horny texture like the annuli. The second 

 or terminal joint [c) is longer and narrower than the preceding 

 one, the internal margin straight and membranous, being pro- 

 longed forwards into a blunt conical point. Upon the outer side 

 of this joint, near to its apex, is a slight depression, which lodges 

 a small brush [d) composed of several short obtuse spines, im- 

 planted upon a rounded elevation within it. What the use 

 of these singular appendages may be, it would be interesting to 

 ascertain. Long bristles, seated upon tubercles, extend outwards 

 from the above joint and are shortest upon its apex. The annuli 

 of the ovipositor are connected together by a tough inteiTening 

 membrane, perfectly distinct from that which lines the entire 

 organ (PI. V. fig. 28. m!), a continuation of the oviduct, and upon 

 which impressions of the rings may be often seen to be faintly 

 traced. Behind, where the annuli cease, the membrane connecting 

 them is reflected outwards and upwards, and it is an extension of 

 this fold over the entire ovipositor which constitutes its next por- 

 tion, or 



The sheath, one indeed of the most remarkable structures that 

 has been as yet met with in Phalangium. It consists of a thin 

 membrane, thrown into transverse folds, and covered over densely 

 throughout nearly its entire extent with short, obtuse and conical 

 spines. Upon viewing it under a low power, this membrane ap- 

 pears as if crossed by numerous lines, and that, at the points 

 where the latter intersect each other, small stars or trident-shaped 

 spines were placed. This, which forms a very beautiful object 

 under the microscope, seems to be, in part, produced by the di- 

 vergent shadows from the really simple conical spines cast upon 

 the membrane beneath, and partly by a curious puckering of the 

 latter around the base of each spine. But that this appearance, 

 whatever be its real production, is false, may be determined by 

 submitting a portion of the sheath to a power of 570 or even 1020 

 linear, when the structure of the spines may be satisfactorily de- 

 monstrated to be such as was just stated; more especially if, as 

 sometimes happens, in placing it between two slips of glass for 



